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Black Ball-point Pen Chromatography Identified

Posted on:2007-08-29Degree:MasterType:Thesis
Country:ChinaCandidate:Q F MaFull Text:PDF
GTID:2206360185464530Subject:Analytical Chemistry
Abstract/Summary:PDF Full Text Request
With the development of computer and internet, electronic communication, electronic signatures and a whole array of electronic business transactions become more and more popular, but the ink- based document remains widely used and trusted for any business and legal documents. So the problem of questioned document remains an very important problem in forensic science. In this article we researched on the classification of 33 kinds of black inks which manufactured by different the domestic and foreign factories. In this project, various types of chromatography for the identification of inks were investigated, including thin-layer chromatography (TLC), high performance liquid chromatography (HPLC) and gas chromatography (GC). First, We summaried the main composition of inks including dyestuff, solvent, resin and resistance to oxidation, heat, light, water, etc. at the same time , recapitulated the discrimination of questioned documents by chromatography including TLC , HPLC and GC.Secondly, We systematical analyzed on the black ball point writing inks with thin-layer chromatography (TLC), high performance liquid chromatography (HPLC) and gas chromatography (GC).TLC is a very popular technique due to the ease of use, speed and cost effectiveness. The retardation factor, Rf value of a compound of ink is dependant on the absorbent and mobile phase, and the number of spots can be used to identify the difference among the inks. In the condition of this experiment, the black ballpoint pens are separated into 12 kinds. The resolution of TLC is limited and can often prove incapable of differentiation between different batches of ink with the same general composition. HPLC will help to improve the ability to distinguish between inks owing to their greater sensitivity and resolving power. We explored a HPLC method to identify these ballpoint pen inks. The method involved the use of a SunFire C-18 column with an acetonitrile: water(NH4HCO3) =60 : 40 (PH=8)mobile phase and a diode array multiwavelength detector scanning from 200-700 nm. Using this approach resulted in greatly improved sensitivity and increased resolution; an the same time, A classifier flowchart was designed for the chromatographic data based on the presence or absence of certain peaks at different wavelengths, HPLC was capable of the detection of subtle batch differences, not...
Keywords/Search Tags:Forensic science, ballpoint pen, inks, thin-layer chromatography (TLC), high performance liquid chromatography (HPLC), gas chromatography (GC)
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